Opinions needed.

i just checked the other pictures, and it's only this single leaf, right? in that case a deficiency, while possible, is rather unlikely.. if there were small spots, then ok, but this looks rather intense already.. i would remove the leaf, and still keep an eye on the new growth and the other leaves to ensure it's not reappearing.. happy growing

if there was damage on any part of the leaves, adjusting the deficiency will not cause the leaf to "heal".. the damage that was done, will stay.. I recommend just removing those leaves, and closely inspecting if anything new appears, then you will know whether you still run into a deficiency or not..

the damage will not go away with the CalMag.. check that your new growth is perfect green like before and your have sorted yourself 👍

Then increase the Cal / Mag in a very small amount and watch it closely :-). the plant itself looks great 🙏🏻👍